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' J. HOWDEN.

AIR SUPPLYING DEVICE FOR STEAM BOILER FURNACES. No. 288,437 Patented Nov. 13, 1883.

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N. PEYERS. Phmniilw n lwr. Wash ngton. at:

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AIR-SUPPLYING DEVICE FOR STEAM-BOILER FURNACES.

SPECIFICATION formingpart of Letters Patent No. 288,437, dated November 13, 1883.

Application filed September 13, 1883. (N0 model.) Patented in England June 14, IFSQ, No. 2,769; in France December 19,1882, No. 152,584, and in Belgium December 19, 188 2, No. 59,9] I.

To aZZ whom, it may concern:

Be it known that 1, JAMES Hownnn, a subject of the Queen of Great Britain and Iremaybe obtained and the great waste of heat may be diminished, which ordinarily takes place in existing arrangements, while my improvements, as applied in connection with marine boilers, have the important advantage of securing ventilation and coolness in the stoke-holds.

In carrying out my invention an important feature is the use, in combination with other devices, of a forced draft to give a more rapid and effective combustion of the coal or other fuel used in the furnaces. The air for combustion is supplied at a pressure above that of the atmosphere, as is done in torpedo boats; but instead of inclosing the entire stokehold and keeping it air-tight under pressure,

which is quite impracticable in large vessels, or even in vessels of moderate size used for ordinary purposes, the air is confined in an airtight casing formed by a false front of thin plates inclosing a space or spaces in front of the furnaces, and at other parts of the boilers where considered necessary or desirable in carrying out my invention with the object of saving heat. In some cases the air in the easing may have access to the furnaces or ashpits just like the air from the stoke-hold in existing arrangements; but in arrangements which I prefer there is in each case a common air-chest or compartment of the casing which is separated by partitions from the furnaces and other parts, while the furnaces are separated from each other, and the supply of air to each is regulated by means of suitable valves. One compartment may be used for admitting air above the fuel of each furnace; also, through tubular fire-bars and into the ash-pit thereof, one valve being used to regulate the admission and for shutting off the supply when fuel has to be introduced or ashes withdrawn, the quantities of air admitted to these several parts being regulated by gratings or valves on the interior doors. 1, however, prefer to admit the air separately, either .above or below the fuel or through the firebars, separate partitions and valves being provided for this purpose. The fire-gases, after passing through or over the heating-surface of the boiler or boilers, may be prevented from passing away too rapidly, which the pressure employed would tend to make them do, by partially closing the ends of the tubes of tubular boilers or analogous parts of other boilers, or the velocity of the escaping gases may be regulated at some part of the passages leading to the chimney or funnel, and the gases may be made to give up a considerable portion of their remaining heat to the air supplied to the common aircasing by being passed through tubular or other suitable passages in a part of the air-casing or in a casing communicatin g therewith, the cold air entering from the fan or other blowing apparatus being made to pass in contact with the outsides of such tubular or other passages. By this means the great heat which would otherwise be lost, as in torpedo-boats, or in ordinary steam-boilers, is utilized in heating the air for combustion, thus effecting a great economy of fuel and obtaining from a much smaller boiler or fire-grate an evaporation of water or supply of steam equal to that from the usual marine-b0iler worked with natural draft, while at the same time the boiler-room or stoke-hold is kept cool and the temperature of the uptakes and funnel is comparatively low. As I prefer to work the fan or blowing apparatus in the stoke-hold, the air therein is always kept cool and fresh by the supply which continually enters to replenish what is taken by the fan; and as the false front of the air-casing which coversthe greater part of the boiler ends is always comparatively cool, no heat from the furnaces or ash-pits is radiated into the stoke-hold, as in ordinarily-fired boilers, or as in torpedoboats,

so that with the shell of the boilers properly protected by a non-conducting material .110

part of the boiler-room can be heated to any great extent from the working of the boilers. In the accompanying drawings, Figure 1 is a front elevation of a marine boiler with onehalf shown in vertical section; and Fig. 2 is a vertical section, as at right angles to Fig. 1.

The fan or blowing apparatus employed in carrying out my invention may be of any suitable known kind, but is not shown in the drawings. The air from the blowing apparatus enters by a pipe, 3, into a space between thei'ront of the boiler itself and an outer shell or casing constructed of thin plating. This space is divided by various plates or partitions, there being an upper horizontal partition, 4, extending completely across the front, and above which is a compartment or space, 5, communicating directly with the uptake 6. Smoke -box compartments 7 are formed in front of the tubes, and these compartments communicate with the top space, 5, through vertical tubes 8. Ahorizontal plate, 9, closes the space between the two smoke-box compartments 7 and another horizontal plate, 10, indicated by dotted lines, closes the top of the space between the outer side of that smokebox compartment which is nearest the air-inlet 3 and the side of the casing, so that the, air entering by the pipe 8 has first to proceed horizontally across the front of the boiler and to pass in contact with the tubes 8, from which it will take up some heat.

The two smoke-box compartments 7 have doors fitted to them to give access for cleaning the tubes, and one, 11, of these doors is shown at the left-hand side of Fig. 1, but is not seen in the sectional half of the figure. After passing horizontally across the front of the boiler, as described, the air, partly warmed by the vertical tubes 8, descends through the space 12, which is between the right-hand smoke-box compartment 7 and the outer side of the air-casing, and spreads over the part of the front of the boiler which is below the smoke-box compartments 7.

A circular casing, 13, is fixed in front of each furnace 14, and also incloses a space in front of the ash-pit l5, and this circular cas ing 13 is formed with two horizontal partitions, forming three compartments or spaces, 16 17 18, within the circular casing. The outer front shell of the air-casing, which covers the larger part of the front of the boiler, practically extends over the casing 13, but is formed with a hinged flap or door, 19, to give access to the ash-pit 15, and is also fitted with a fire-door, 20. This fire-door 20 has fixed to it by studs an inner door 61' plate, 21, for closing the opening from the air-space into the furnace 14.

The opening for the outer fire-door, 20, is made larger than that for the inner door, 21, so that the inner door may easily open outward along with the outer door, and the inner door 1s formed with perforations to admit air, and with inclined plates on its inner side to deflect the entering air downward on the fuel.

The perforations in the inner fire-door, 21, to a certain extent control the quantity of air entering above the grate-bars; but in addition I prefer to use an adjustable valve, 22, for regulating the proportion of air which passes from the main space of the air-casing into the compartment 16, in which the fire-doors 2O 21 are situated.

The air which enters the middle compartment, 17, and which can be regulated by means of valves 23, has access from that compartment either into tubular fire-bars communicating with orifices in the bridge or into hollow bars 24, of which there is one extending along each side of each furnace 14. These hollow side bars are a little higher than the grate-bars, and are perforated for the issue of the air from them into the furnace. The lower air-compartment, 18, which communicates with. the ash-pit 15, is also provided with valves 25 for regulating the proportion of air entering that way.

\Vith these arrangements the air may be distributed to the different parts of the furnace in the respective proportions which may be found to give the best results.

\Vhat I claim as my invention of air-supplying devices for steam-boilers is- 1. In combination, a fan or blower, an air casing or space through which the air is forced, such space having tubes for the waste fire-gases to pass through, and partitions in the air-casing forming in front of each furnace and ash-pit compartments fitted with valves for the separate regulation of air pass ing therethrough into the furnace above the grate-bars into hollow bars and into the ash pit, the various parts being arranged and operating substantially as and for the purposes herein set forth.

2. In combination, a fan or blower to supply air under pressure, and an air-casing formed upon. the front of a steam-boiler to prevent overheating of the stokehold and to utilize the heat radiated from the front of the boiler in heating the air-supply, substantially as herein set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses. 7

JAMES HOXVDEN.

Vitnesses:

EDMUND HUNT, D. FnncUsoN. 

